Account not receiving emails

Added a Gmail account and my ISP account (Centurytel/Centurylink) to eM client. Gmail email is set as the default and receiving emails just fine.

 But my ISP account has never received any emails and there is sometimes a pop up telling me about POP3 settings for the ISP account. I’m using the same settings that have been used for years in another email client.

Hello Jack,

What version of eM Client are you using? 
I would recommend either running the Diagnostic feature that is in Menu > Tools > Accounts > Diagnostics and if it doesn’t help, please try deleting the account and adding it again manually.